Plasma erythropoietin in newborn lambs.

In the present study early postnatal changes in erythropoietin (Epo) level and hemoglobin concentration in 8 lambs were examined. Plasma Epo was estimated by a monoclonal enzyme-immunoassay (ELISA), developed for human Epo. In all the lambs, except one, Epo was low, or undetectable, immediately after birth. Within 6-12 h after birth, a marked increase in plasma Epo was found in 4 of the lambs. Within 3-7 days after birth, Epo was back to low levels. In the lamb with high Epo levels at birth, drastic decreases were observed during the next 6 h. There was no obvious correlation between the hemoglobin concentrations and the changes in plasma Epo.